Question asked 2017-02-25 09:31:58 ...
Most recent comment 2017-03-03 14:52:00
Solvents and Thinners
I make a point of searching out and buying a 190 proof (95% ethanol) denatured alcohol for making shellac. However many of the denatured alcohols sold at hardware stores contain lesser percentages of ethanol (i.e. a student just asked me about "Sunnyside" brand; the MSDS reveals it is only 86% ethanol). If someone prefers to buy whatever denatured alcohol is available at their local hardware store, at what percentage number does the ethanol in the formulation become too low to be suitable as a thinner for shellac?
Also, the MSDS for Sunnyside's denatured alcohol lists "hazardous ingredients", which add up to about 94%. What is the other 6% or so percent composed of?
Answers and Comments
Unfortunately, I cannot give you an authoritative answer but I have asked
one of our other moderators to comment.
In the meantime, here is my unofficial estimation of what is going on. Most likely,
this denatured alcohol is 86% ethanol and 8% of another non-consumable solvent (methanol
in England but there are other options) which is used as the denaturing
component. The aim here is not to make a poor shellac solvent (really the only
general use today of denatured alcohol is for shellac and alcohol burners), but
to render the solvent unable to be used as an intoxicant. The remainder is
I have personally dissolved everything from stick, seed, orange, garnet, and
dewaxed blonde shellac in hardware store brand denatured ethanols without
problems or precipitation. Shellac is not completely soluble in ethanol of
too low a proof resulting in in a turbid, white semi-solution. You
can witness the same effect by adding water to a dissolved
solution of shellac. The resin will
precipitate out of solution when the proportion of ethanol drops too low.
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